This invention relates to a technology for managing data stored in a storage system, in particular, a technology for managing a journal in a storage system having a snapshot function.
Known as functions included in a storage system are a snapshot function and a journal function.
The snapshot function is a function of retaining an image of a given logical volume at a given time point (for example, at a time point when a snapshot acquisition request is received from a host). Periodic execution of the snapshot function makes it possible to intermittently acquire a replication (in other words, backup) of data within the logical volume. In addition, the snapshot function enables restoration of the logical volume at a snapshot acquisition time point.
The journal function is a function of creating and saving a journal, which is data containing write data and control information regarding the writing, in a case where the write data is written into a logical volume specified by a write command issued from a host computer.
JP 2005-18738 A discloses a recovery processing executed at a point other than a point at which a snapshot is created, by having write data within a journal written into the snapshot acquired by the snapshot function.
JP 2007-80131 A discloses a technology related to switching between a snapshot and a journal.
JP 2007-133471 A discloses a technology related to operation of a volume for restoring a snapshot.